Page 115 - Sustainable Cities and Communities Design Handbook

92 Sustainable Cities and Communities Design Handbook

capacity, trailed by Iowa, California, and Oklahoma. Seventeen states have
greater than 1 GW of installed capacity, and in 12 states, wind energy accounts
for at least 10% of in-state power production (Wind Technologies Market
Report, 2015).
Although the wind power resource in the United States is substantial, it is
also, significantly, distributed across the continent with substantial variation.
Although several areas, particularly in the East and West coasts, feature a
coincidence of both strong continental wind resources and high-density pop-
ulation centers, the broadest swath of wind resource is located in the plains
states, whose low population levels and densities decrease the economic
efficiency of employing those wind resources locally. Capitalizing on the
resources of the plains will require the build-out of expensive transmission
lines, increasing a given project’s expense and challenging its viability.
Offshore wind resources, which are generally stronger and steadier than their
continental counterparts, have also attracted the attention of wind power
developers. However, the cost of electricity produced by offshore wind plants
is thought to be about three to four times greater than that produced by
terrestrial systems, due to higher costs across the breadth of construction,
including turbine manufacturing and installation (Wind Technologies Market
Report, 2015; National Offshore). In addition, the added expense of undersea
transmission lines further diminishes the attractiveness of investment in
offshore systems.
Although utility-scale turbines dominate the US wind market, distributed
wind installations can be found in all 50 states. Although large installations
(greater than 1 MW) are the primary source of distributed capacity addition in
the last decade, small wind installations (under 100 kW) are an active portion
of the sector. In 2015, domestic small turbine installations grew by 16%,
placing an additional 4.3 MW in service (Distributed Wind Market Report,
2015). By number of projects, the most common contexts of distributed
systems built in recent years are agricultural and residential, whereas by total
power capacity, the most common applications are industrial and commercial.
Uncertainty about state and federal subsidies and competition with solar
photovoltaics and natural gas may inhibit the expansion of wind power in
distributed systems.

SOLAR
The sun is the primary energy input for virtually all processes, biological and
otherwise, that occur on the earth’s surface. While in the broadest sense
several of the energy sources currently employed todaydwind, biomass, and
fossil fuelsdhave a solar genesis, there is a class of technologies that
directly converts electromagnetic energy from the sun into useful energy.
The two main categories of such technology are solar photovoltaics and solar
thermal.